1. Technical Field
This disclosure generally relates to computer systems, and more specifically relates to compilers that generate executable code for computer systems.
2. Background Art
Computer systems have evolved into extremely sophisticated devices, and computer systems may be found in many different settings. Dramatic advances in both hardware and software (e.g., computer programs) have drastically improved the performance of computer systems. Modern software has become very complex when compared to early computer programs. Many modern computer programs have tens or hundreds of thousands of instructions. The execution time (and hence, performance) of a computer program is very closely related to the number and complexity of instructions that are executed as the computer program runs. Thus, as the size and complexity of computer programs increase, the execution time of the computer program increases as well.
Unlike early computer programs, modern computer programs are typically written in a high-level language that is easy to understand by a human programmer. Special software tools known as compilers take the human-readable form of a computer program, known as “source code”, and convert it into “machine code” or “object code” instructions that may be executed by a computer system. Because a compiler generates the stream of machine code instructions that are eventually executed on a computer system, the manner in which the compiler converts the source code to object code affects the execution time of the computer program.
The execution time of a computer program, especially complex computer programs, is a function of the arrangement and type of instructions within the computer program. Many different optimizations have been developed so the code produced by compilers has better run-time performance. One such optimization is converting scalar instructions, such as those in a loop, to vectorized instructions, known as vectorization. Known vectorization methods can produce vectorized code that actually reduces the performance of the computer program.